It is known that a photosensitive material, such as photoresist, may be employed to selectively apply a coating to portions of a substrate. Such methods typically begin by depositing a coating, such as a conductor, onto a substrate. This coating typically covers the entire substrate surface and requires selective removal in order to pattern the coating. Next, a photoresist is coated onto the substrate. A mask is then placed over the substrate to define the desired pattern. Light rays are directed toward the mask, and those portions of the photoresist that are not covered by the mask are exposed to the light while portions which are covered by the mask are not. Either the exposed or unexposed portions of the photoresist are then removed, depending upon whether a "positive" or "negative" type of photoresist is used. Those portions of the coating which are no longer covered by the photoresist may then be removed, such as by chemical etching or other means. The remaining photoresist is then removed, leaving only the coating covering the desired locations on the substrate.
The mask method described above may also be used to remove a coating from either the upper or lower levels of a bilevel substrate. However, this requires both the creation of a mask capable of achieving a pattern identical to the physical pattern of the bilevel substrate and the ability to properly align the mask in registration with the physical pattern of the substrate surface. The disadvantage of this approach is that as the distances between the raised portions of the substrate become increasingly small (e.g., on the order of 500 .mu.m or less), the problem of aligning the mask and the substrate surface becomes increasingly large. In addition, the processes of mask alignment, exposure, and photoresist removal are both time consuming and prone to produce defects in the resultant patterned coating due to process variability.